a) Field of the Invention
The present invention relates to a vehicle windshield wiper blade assembly and a wiper system including such a wiper blade assembly, suitably usable in cold districts or winter season, and more particularly, to a vehicle windshield wiper blade assembly and wiper system, which can be operated with no adhesion of ice, snow or the like (hereafter "snow") to the wiper blade andwith a constantly high wiping efficiency when the vehicle is running at a high speed.
Also the present invention relates to a vehicle windshield wiper blade assembly which can smoothly follow and positively wipe the surface of a vehicle windshield including surfaces of which the radii of curvature are relatively small.
b) Prior Art Statement
For clear understanding how the vehicle windshield wiper blade assembly and a wiper system including such a wiper blade assembly are constructed and work, a typical one of the conventional ordinary vehicle windshield wiper blade assemblies and wiper systems will be described with reference to FIGS. 1 through 4.
In FIGS. 1-4 an automobile windshield to be wiped by the wiper blade ("windshield") is generically indicated by the reference numeral 1. Generally, the windshield 1 includes a plurality of surfaces different in radius of curvature from each other to meet the aerodynamic and esthetic requirements.
The windshield I is wiped by a blade rubber 2 made of, for example, a rubber. As shown in FIG. 3, the blade rubber 2 comprises a wiping portion 20 intended to wipe the windshield I and of which the cross section has the general form of an inverted triangle, a retaining portion 21 of which the cross-sectional shape is generally a trapezoid, and a neck portion 22 formed integrally with, and between, the top of the wiping portion 20 and the bottom of the retaining portion 21. The wiping portion 20 of the blade rubber 2 has formed at the free end (bottom) thereof a lip portion which is kept tilted to the left (or right) as shown in FIG. 3 as always pressed to the windshield 1 by the elastic material forming a wiper drive 8.
The blade rubber 2 is held by a backing channel 3 made of, for example, a synthetic resin. As shown in FIG. 3, the backing channel 3 has a generally C-shaped cross-section which fits on the retaining portion 21 of the blade rubber 2 and has formed in the bottom thereof a cut 30 of which the width is somewhat larger than the thickness of the neck portion 22 of the blade rubber 2. The backing channel 3 is loosely fitted on the retaining portion 21 of the blade rubber 2 so as to be movable in relation to the retaining portion 21. Thus the neck portion 22 of the blade rubber 2 is so positioned in the cut 30 in the backing channel 3 as to be movable in relation to the backing channel 3. The blade rubber 2 is thus held by the backing channel 3. However, it should be noted that the backing channel 3 may not always be necessary or it may be made of a metal.
The reference numeral 4 indicates a primary lever made of a thin steel plate, for example, bent to have a top plate portion and right and left side plate portions. The primary lever 4 has formed nearly in the center of the top plate portion thereof an opening 40 in which there is set a clip 44. The clip 44 is pivotably installed to the right and left side plate portions corresponding to the opening 40 in the primary lever 4 by means of a rivet 43 generally parallel to the windshield 1. In addition, the primary lever 4 has formed in the top plate portion thereof to the right and left of the opening 40 a plurality (e.g., 7) of generally rectangular through-holes 47. The through-holes 47 may not always be formed.
The reference numeral 5 indicates a secondary lever also made of a thin steel plate, for example, bent to have a top plate portion and right and left side plate portions. Two such levers 5 are provided. Each of the secondary levers 5 has an engagement pawl 50 formed at one end thereof (outer one at which the secondary levers 5 are installed to the primary lever 4). Each of these two secondary levers 5 is pivotably installed nearly at the center thereof to each end of the primary lever 4 by means of a rivet 51 generally parallel to the windshield 1.
The reference numeral 6 indicates a yoke also made of a thin steel plate, for example, bent to have a top plate portion and right and left side plate portions. Two such yokes 6 are provided. Each of the yokes 6 has an engagement pawl 60 formed at either end thereof. Each of these yokes 6 is pivotably installed nearly at the center thereof to the other end of each secondary lever 5 (inner one at which the yokes 6 are installed to the primary lever 4) by means of a rivet 61 generally parallel to the windshield 1.
The engagement pawls 50 of the secondary levers 5 and those 60 of the yokes 6 are made by bending their respective lower ends inwardly about 90 degrees. The clearances 52 and 62 between the ends of the engagement pawls 50 and 60, respectively, thus bent are a little larger than the thickness of the neck portion 22 of the blade rubber 2. The engagement pawls 50 and 60 of the secondary levers 5 and yokes 6, respectively, are loose-fitted on the backing channel 3 so as to be movable in relation to the latter. The neck portion 22 of the blade rubber 2 is so inserted in the spaces 52 between the inner ends of the engagement pawls 50 of the secondary levers 5 and the spaces 62 between the ends of the engagement pawls 60 of the yokes 6 as to be movable in relation to the pawls 50 and 60. In this manner, the engagement pawls 50 at the outer end of the secondary levers 5 and the engagement pawls 60 at the opposite ends of the yokes 6 are engaged on the blade rubber 2 and backing plate 3, respectively.
As having been described in the foregoing, the blade rubber 2 is supported at 6 points, namely, with two engagement pawls 50 of the secondary levers 5 and four engagement pawls 60 of the yokes 6. When a yoke 6 is installed to either end of each of the two secondary levers 5 and the blade rubber 2 is supported at either end of each of the four yokes 6, the blade rubber 2 is supported at 8 points. Moreover, in case the blade rubber 2 is supported at either end of each of the two secondary levers 5, not by means of the yokes 6, the supporting points of the blade rubber 2 count 4 in number.
The aforementioned secondary levers 5 and yokes 6 support together the blade rubber 3 (and the backing channel 3) at a plurality of points (6 points in the above-mentioned case).
The blade rubber 2, backing channel 3, primary lever 4, secondary levers 5 and yokes 6 form together a wiper blade (or wiper blade assembly).
In FIG. 1, the reference numeral 8 indicates a wiper drive. The wiper drive 8 is coupled to a drive shaft (not shown) of a motor (not shown), and it consists of a wiper shaft 80 extending generally perpendicularly to the windshield 1, arm head 81 fixed to the wiper shaft 80, wiper arm 83 installed pivotably to the arm head 80 by means of a hinge pin 82 nearly perpendicular to the wiper shaft 80, and an elastic member (not shown) interposed between the wiper arm 83 and arm head 81 to always press the wiper arm 83 toward the windshield 1. The end of the wiper arm 83 is removably connected to the clip 44 of the primary lever 4 of the wiper blade assembly.
When the wiper blade is attached to the wiper arm 83 of the wiper drive 8, a vehicle windshield wiper system is formed.
The vehicle windshield wiper system thus assembled functions as will be described below:
When the wiper motor of the wiper drive is put into run, the wiper blade will reciprocally move at a high speed, at a low speed or intermittently in the direction of arrow D in FIGS. 2 through 4 (opening direction, namely, forward) and in the direction of arrow E (closing direction, namely, backward) to wipe the windshield I with the wiping portion 20 of the blade rubber 2. In this windshield wiper system, when the blade rubber 2 is stopped from reciprocal wiping motion and the wiper blade is placed in the home position (when the wiper drive 8 is stopped), the wiper blade is directed downward in the direction of arrow E.
A vehicle wiper system for use in cold districts or winter season is known from the disclosure in the Japanese Unexamined Utility Model Publication No. 49-148627. In this vehicle windshield wiper system, a stay connecting a wiper blade body (comprising a blade rubber, support members and a cover covering the support member and a part of the blade rubber) and the wiper arm to each other is formed like such a vane that the wiper blade body is pressed toward the windshield surface under a window pressure applied to the stay when the vehicle runs at a high speed. In this vehicle wiper system, the cover provided prevents snow from adhering to the support members and the vane-like stay prevents the wiper blade body from leaving the windshield surface as caused by a wind pressure applied when the vehicle runs.